Cell surface membranes mediate interactions between cells, such as cell-cell recognition, adhesion, and alignment, that may depend upon highly organized molecular complexes within the membrane or exposed at the membrane inner or outer surface. Abnormal interactions between malignant and host cells or host effector mechanisms may be the result of compositional and/or structural abnormalities in the molecules that comprise the external architecture of membranes. Quantitative methods utilizing computer facilitated analyses of one and two dimensional IEF/SDS gel electrophoresis and HPLC have been established to characterize the protein, glycoprotein, lipid, and glycolipid components of normal and transformed cell membranes and to determine the molecular basis of membrane changes that may occur in response to the treatment of cells with chemical and physical carcinogens, co-carcinogens, modulators, lymphokines, and other immunobiological effectors. These studies have demonstrated that treatment with the lymphokine, lymphotoxin, stimulates the synthesis of high molecular weight membrane glycoproteins in normal cells and decreases incorporation of glucosamine into high molecular weight glycoproteins in malignantly transformed cells without significantly altering membrane protein composition in either cell type.